Double-layer boiler heating surface structure based on molten salt heat buffering

Abstract

The application discloses a double-layer boiler heating surface structure based on fused salt heat buffering, which comprises a normal-pressure heating layer and a high-pressure heating layer, the high-pressure heating layer is located in the normal-pressure heating layer, and a fused salt heat buffering layer is arranged between the normal-pressure heating layer and the high-pressure heating layer. The structure can guarantee safe operation of the heating surface when the unit load rapidly changes.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation technology and relates to a double-layer boiler heating surface structure based on molten salt thermal buffer. Background Technology

[0002] Boiler heating surfaces refer to the intermediate medium surfaces through which the heat from the combustion of fuel in the furnace is continuously absorbed and transferred to water, steam, and air during combustion. During normal operation, boiler systems are susceptible to fluctuations in coal type and quality, air distribution disturbances, and rapid load increases and decreases. Mismatches in heat exchange between the furnace radiation and flue gas convection and the boiler heating surfaces, as well as between the heating surfaces and the working fluid, can easily lead to excessively high heating surface wall temperatures. Furthermore, with the increasing capacity of new energy power generation, more and more coal-fired power plants need to participate in peak shaving. The internal pressure and external temperature of superheaters and reheaters must withstand rapid changes, severely impacting the lifespan of the boiler's heating surfaces. In severe cases, frequent tube ruptures can occur, easily leading to unplanned outages and affecting the safe and stable operation of the boiler unit. With the rapid development of various new energy power generation methods, traditional thermal power generating units inevitably play a role in grid peak shaving.

[0003] A prior art publication (CN102269396A) discloses a boiler heating surface arrangement structure. Specifically, it features at least two different boiler heating surfaces arranged side-by-side in the same flue gas temperature region within the boiler's independent flue. These at least two different heating surfaces can be located at different positions within the same steam-water flow path, or they can be located in different steam-water flow paths. The at least two different heating surfaces can be arranged in a crisscrossing arrangement within the same flue gas temperature region of the boiler's independent flue. Alternatively, they can be arranged in a front-to-back arrangement, a left-to-right arrangement, or a combination of at least two of these arrangements within the same flue gas temperature region of the boiler's independent flue. The effect is that by arranging different heating surfaces from the same or different steam-water processes in the same flue gas temperature range of the boiler flue, the heat transfer temperature difference of the boiler heating surfaces can be fully utilized, improving the heat absorption efficiency of the boiler heating surfaces and ultimately improving the heat exchange efficiency. This existing technology uses multiple heating surfaces arranged in different locations to handle different steam-water processes, but it still cannot solve the problem that the internal pressure and external temperature of the superheater and reheater must withstand rapid changes, seriously affecting the lifespan of each heating surface in the boiler, and in severe cases, causing frequent tube rupture incidents. Therefore, the design of the heating surfaces of existing thermal power generating units should consider the safe operation of the heating surfaces under rapid load changes, ensuring the safe and stable operation of the boiler unit under long-term peak-shaving operation. However, existing technologies do not provide technical solutions to address these problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a double-layer boiler heating surface structure based on molten salt thermal buffer, which can ensure the safe operation of the heating surface when the unit load changes rapidly.

[0005] To achieve the above objectives, the double-layer boiler heating surface structure based on molten salt thermal buffer of the present invention includes an atmospheric pressure heating layer and a high pressure heating layer, wherein the high pressure heating layer is located inside the atmospheric pressure heating layer, and a molten salt thermal buffer layer is provided between the atmospheric pressure heating layer and the high pressure heating layer.

[0006] A further improvement to the double-layer boiler heating surface structure based on molten salt thermal buffer described in this invention is as follows:

[0007] Furthermore, the atmospheric pressure heating layer includes several cuboid cavities, wherein each cavity contains one or more tubes of the high pressure heating layer.

[0008] Furthermore, the distance between the sidewall of the cavity and the outer boundary of the tube bank of the high-pressure heating layer is 20mm.

[0009] Furthermore, a Z-shaped high-temperature molten salt equalization tube is arranged between adjacent rows of cavities.

[0010] Furthermore, the inclined section of the Z-shaped high-temperature molten salt equalization tube has an angle of 30°-50° with the horizontal direction.

[0011] Furthermore, it also includes a high-temperature molten salt overflow pipe and a molten salt buffer chamber. The lowest end of the atmospheric pressure heating layer is provided with a high-temperature molten salt overflow port, which is connected to the high-temperature molten salt overflow pipe. The outlet of the high-temperature molten salt overflow pipe is connected to the molten salt buffer chamber.

[0012] Furthermore, the high-temperature molten salt overflow pipe is distributed with an upward tilt of 20°.

[0013] Furthermore, a pressure relief valve is arranged on the molten salt buffer chamber.

[0014] Furthermore, the molten salt heat buffer layer serves to transfer heat, while the atmospheric pressure heating layer withstands high temperature, its own weight, and the gravity of the molten salt; the high pressure heating layer withstands the high pressure of the working fluid and the heat transfer from the boiling molten salt.

[0015] The double-layer boiler heating surface structure based on molten salt thermal buffer described in this invention includes a high-temperature molten salt overflow pipe, a molten salt buffer chamber, an atmospheric pressure heating layer, and a high-pressure heating layer. The high-pressure heating layer is located inside the atmospheric pressure heating layer, and a molten salt thermal buffer layer is provided between the atmospheric pressure heating layer and the high-pressure heating layer.

[0016] The atmospheric pressure heating layer contains several rectangular cavities, wherein a single cavity can accommodate one or more tubes of the high pressure heating layer, and a Z-shaped high-temperature molten salt equalization tube is arranged between two adjacent rows of cavities.

[0017] The lowest end of the atmospheric pressure heating layer is provided with a high-temperature molten salt overflow port, which is connected to a high-temperature molten salt overflow pipe. The outlet of the high-temperature molten salt overflow pipe is connected to the molten salt buffer chamber.

[0018] The present invention discloses a boiler, the boiler including the double-layer boiler heating surface structure based on molten salt heat buffer, the double-layer boiler heating surface structure based on molten salt heat buffer includes an atmospheric pressure heating layer and a high pressure heating layer, the high pressure heating layer is located inside the atmospheric pressure heating layer, and a molten salt heat buffer layer is provided between the atmospheric pressure heating layer and the high pressure heating layer.

[0019] The present invention has the following beneficial effects:

[0020] The double-layer boiler heating surface structure based on molten salt thermal buffering described in this invention includes an atmospheric pressure heating layer and a high-pressure heating layer. The high-pressure heating layer is located inside the atmospheric pressure heating layer, and a molten salt thermal buffering layer is set between the atmospheric pressure heating layer and the high-pressure heating layer. This optimizes the traditional single-layer heating surface that bears both temperature and pressure into a double-layer heating surface composed of an atmospheric pressure heating layer, a molten salt thermal buffering layer, and a high-pressure heating layer. The atmospheric pressure heating layer only needs to bear the high temperature, its own weight, and the weight of the molten salt; the high-pressure heating layer only needs to bear the high pressure of the working fluid and the heat transfer of the boiling molten salt. This ensures that the high-pressure heating layer will not experience overheating of the heating surface metal when the unit load fluctuates rapidly, thus extending the service life of the heating surface and ensuring the safe and stable operation of the boiler unit.

[0021] Furthermore, a Z-shaped high-temperature molten salt equalization tube is arranged between two adjacent rows of cavities. The angle between the inclined section of the Z-shaped high-temperature molten salt equalization tube and the horizontal direction is 30°-50°. By setting the Z-shaped high-temperature molten salt equalization tube, the high-temperature molten salt inside the atmospheric pressure heating layer can be homogenized. At the same time, it can enhance the disturbance of flue gas flow when passing through the heating surface, avoid the formation of flue gas corridors, and enhance the heat exchange between flue gas and the heating surface.

[0022] Furthermore, the distance between the sidewall of the cavity and the outer boundary of the high-pressure heating layer is 20mm to allow for the expansion of the high-pressure heating layer.

[0023] Furthermore, a pressure relief valve is installed on the molten salt buffer chamber. When the pressure inside the molten salt buffer chamber exceeds 1.5 atmospheres, the pressure relief valve opens to prevent the risk of explosion due to excessive pressure in the atmospheric pressure heated layer. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a cross-sectional view of the present invention;

[0026] Figure 2 This is a structural diagram of the present invention;

[0027] Figure 3 for Figure 2 Cross-sectional view along the AA direction.

[0028] Among them, 1 is the boiler furnace, 2 is the atmospheric pressure heating layer, 3 is the high pressure heating layer, 4 is the high temperature molten salt overflow pipe, 5 is the molten salt buffer chamber, 6 is the pressure relief valve, 7 is the molten salt thermal buffer layer, and 8 is the Z-shaped high temperature molten salt equalization pipe. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0031] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0033] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0034] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0037] Example 1

[0038] refer to Figure 2 The double-layer boiler heating surface structure based on molten salt thermal buffering described in this invention is characterized by comprising a high-temperature molten salt overflow pipe 4, a molten salt buffer chamber 5, an atmospheric pressure heating layer 2, and a high-pressure heating layer 3. The high-pressure heating layer 3 is located within the atmospheric pressure heating layer 2, and a molten salt thermal buffer layer 7 is provided between the atmospheric pressure heating layer 2 and the high-pressure heating layer 3. The atmospheric pressure heating layer 2 contains several rectangular cavities, wherein a single cavity can accommodate one or more pipe rows of the high-pressure heating layer 3, and a Z-shaped high-temperature molten salt equalization pipe 8 is arranged between adjacent rows of cavities. A high-temperature molten salt overflow port is provided at the very end of the atmospheric pressure heating layer 2, and the high-temperature molten salt overflow port is connected to the high-temperature molten salt overflow pipe 4. The outlet of the high-temperature molten salt overflow pipe 4 is connected to the molten salt buffer chamber 5.

[0039] It should be noted that the double-layer heating surface in this invention includes an atmospheric pressure heating layer 2, a molten salt heat buffer layer 7, and a high-pressure heating layer 3. The atmospheric pressure heating layer 2 only needs to withstand high temperature, its own weight, and the weight of the molten salt; the high-pressure heating layer 3 only needs to withstand the high pressure of the working fluid and the heat transfer of the boiling molten salt. This ensures that the high-pressure heating layer 3 will not experience overheating of the heating surface metal when the unit load fluctuates rapidly. By having different heating layers bear the corresponding loads, the service life of the heating surface is extended, ensuring the safe and stable operation of the boiler unit.

[0040] Example 2

[0041] refer to Figure 1 , Figure 2 and Figure 3 The double-layer boiler heating surface structure based on molten salt heat buffering described in this invention includes an atmospheric pressure heating layer 2 and a high-pressure heating layer 3. The high-pressure heating layer 3 is located inside the atmospheric pressure heating layer 2. A molten salt heat buffer layer 7 is provided between the atmospheric pressure heating layer 2 and the high-pressure heating layer 3. The molten salt heat buffer layer 7 plays a role in efficiently transferring heat. The atmospheric pressure heating layer 2 only needs to withstand high temperature, its own weight, and the weight of the molten salt. The high-pressure heating layer 3 only needs to withstand the high pressure of the working fluid and the heat transfer of the boiling molten salt, without the risk of overheating.

[0042] As one embodiment of the present invention, along the flue gas flow path in the horizontal flue of the boiler, the atmospheric pressure heating layer 2 contains several rectangular cavities, wherein a single cavity can accommodate one or more tubes of the high pressure heating layer 3, and the distance between the side wall of the cavity and the outer boundary of the tubes of the high pressure heating layer 3 is 20mm, so as to allow the high pressure heating layer 3 to expand.

[0043] In one embodiment of the present invention, a Z-shaped high-temperature molten salt equalization tube 8 is arranged between two adjacent rows of cavities. The inclined section of the Z-shaped high-temperature molten salt equalization tube 8 has an angle of 30°-50° with the horizontal direction. This can promote the homogenization of high-temperature molten salt inside the atmospheric pressure heating layer 2, while also promoting flue gas disturbance and avoiding the formation of flue gas corridors. In addition, the angle between the inclined section of the Z-shaped high-temperature molten salt equalization tube 8 and the horizontal direction is adjusted according to the size of the installation position.

[0044] In one embodiment of the present invention, a high-temperature molten salt overflow port is provided at the far end of the atmospheric pressure heating layer 2. The high-temperature molten salt overflow port is connected to the high-temperature molten salt overflow pipe 4. The high-temperature molten salt overflow pipe 4 is distributed with an upward inclination of 20°. The outlet of the high-temperature molten salt overflow pipe 4 is connected to the molten salt buffer chamber 5.

[0045] In one embodiment of the present invention, a pressure relief valve 6 is arranged on the molten salt buffer chamber 5. When the pressure inside the molten salt buffer chamber 5 is greater than 1.5 atmospheres, the pressure relief valve 6 opens to avoid the risk of explosion due to excessive pressure in the atmospheric pressure heating layer 2.

[0046] In one embodiment of the present invention, the boiling point of the molten salt in the molten salt heat buffer layer 7 is the long-term allowable operating temperature T-30℃ of the high-pressure heating layer 3.

[0047] The principle and working process of this invention:

[0048] This invention optimizes the traditional single-layer heating surface that bears both temperature and pressure into a double-layer heating surface composed of an atmospheric pressure heating layer 2, a molten salt heat buffer layer 7, and a high-pressure heating layer 3. The atmospheric pressure heating layer 2 only needs to bear the high temperature, its own weight, and the weight of the molten salt; while the high-pressure heating layer 3 only needs to bear the high pressure of the working fluid and the heat transfer of the boiling molten salt. This ensures that the high-pressure heating layer 3 will not experience overheating of the heating surface metal when the unit load fluctuates rapidly, thus extending the service life of the heating surface and ensuring the safe and stable operation of the boiler unit. Meanwhile, a Z-shaped high-temperature molten salt equalization tube 8 is arranged between two adjacent rows of cavities. The inclined section of the Z-shaped high-temperature molten salt equalization tube 8 has an angle of 30-50° with the horizontal direction. This can promote the homogenization of high-temperature molten salt inside the atmospheric pressure heating layer 2, while also promoting flue gas disturbance and avoiding the formation of flue gas corridors. By setting the Z-shaped high-temperature molten salt equalization tube 8, the homogenization of high-temperature molten salt inside the atmospheric pressure heating layer 2 can be promoted. At the same time, it can enhance the disturbance of flue gas flow when passing through the heating surface, avoid the formation of flue gas corridors, and enhance the heat exchange between flue gas and the heating surface.

[0049] In summary, this invention can ensure that all heating surfaces of the boiler operate within their allowable temperature range under various operating conditions and drastic changes in boiler load, avoiding the risk of tube rupture caused by overheating of the heating surfaces, and achieving safe, stable, efficient and environmentally friendly operation of the boiler unit under varying loads and multiple conditions.

[0050] Example 3

[0051] This embodiment discloses a boiler, which includes a double-layer boiler heating surface structure based on molten salt heat buffer. The double-layer boiler heating surface structure based on molten salt heat buffer includes an atmospheric pressure heating layer 2 and a high pressure heating layer 3. The high pressure heating layer 3 is located inside the atmospheric pressure heating layer 2, and a molten salt heat buffer layer 7 is provided between the atmospheric pressure heating layer 2 and the high pressure heating layer 3.

[0052] Specifically, the atmospheric pressure heating layer 2 includes several rectangular cavities, each cavity containing one or more tube banks of the high-pressure heating layer 3; the distance between the sidewall of the cavity and the outer boundary of the tube bank of the high-pressure heating layer 3 is 20mm; a Z-shaped high-temperature molten salt equalization pipe 8 is arranged between adjacent rows of cavities; the inclined section of the Z-shaped high-temperature molten salt equalization pipe 8 forms an angle of 30°-50° with the horizontal direction; it also includes a high-temperature molten salt overflow pipe 4 and a molten salt buffer chamber 5. The atmospheric pressure heating layer 2... At the very end, a high-temperature molten salt overflow port is provided, which is connected to a high-temperature molten salt overflow pipe 4. The outlet of the high-temperature molten salt overflow pipe 4 is connected to a molten salt buffer chamber 5. The high-temperature molten salt overflow pipe 4 is inclined upward at 20°. A pressure relief valve 6 is arranged on the molten salt buffer chamber 5. The molten salt heat buffer layer 7 plays a role in transferring heat. The atmospheric pressure heating layer 2 bears the high temperature, its own weight, and the weight of the molten salt. The high pressure heating layer 3 bears the high pressure of the working fluid and the heat transfer of the boiling molten salt.

[0053] It should be noted that the boiler described in this invention adopts a double-layer boiler heating surface structure based on molten salt thermal buffer, which can effectively improve the boiler's safety and lifespan, and ensure the safe and stable operation of the boiler unit under long-term peak-shaving operation.

[0054] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0055] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0056] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A double-pipe boiler heating surface structure based on molten salt thermal buffering, characterized by, The application relates to a high-temperature molten salt heat storage device, which comprises a normal-pressure heated layer (2) and a high-pressure heated layer (3), wherein the high-pressure heated layer (3) is arranged in the normal-pressure heated layer (2), a molten salt heat buffer layer (7) is arranged between the normal-pressure heated layer (2) and the high-pressure heated layer (3), the normal-pressure heated layer (2) comprises a plurality of cuboid cavities, each cavity contains a single or multiple high-pressure heated layer (3) tube rows, Z-shaped high-temperature molten salt balance tubes (8) are arranged between two adjacent cavity rows, the normal-pressure heated layer (2) is provided with a high-temperature molten salt overflow pipe (4) and a molten salt buffer bin (5), the last end of the normal-pressure heated layer (2) is provided with a high-temperature molten salt overflow port, the high-temperature molten salt overflow port is communicated with the high-temperature molten salt overflow pipe (4), the outlet of the high-temperature molten salt overflow pipe (4) is communicated with the molten salt buffer bin (5), the molten salt heat buffer layer (7) plays a heat transfer function, the normal-pressure heated layer (2) bears high temperature, self gravity and molten salt gravity, and the high-pressure heated layer (3) bears working medium high pressure and boiling molten salt heat transfer. The distance between the side wall of the cavity and the outer boundary of the high-pressure heated layer (3) tube row is 20mm. The angle between the inclined section of the Z-shaped high-temperature molten salt balance tube (8) and the horizontal direction is 30-50 degrees. The high-temperature molten salt overflow pipe (4) is upwardly inclined by 20 degrees. A pressure relief valve (6) is arranged on the molten salt buffer bin (5).

2. The fused salt heat buffer based double- walled boiler heating surface structure according to claim 1, characterized in that, ​ 3. The fused salt heat buffer based double- walled boiler heating surface structure according to claim 1, characterized in that, ​ 4. The fused salt heat buffer based double- walled boiler heating surface structure according to claim 1, characterized in that, ​ 5. The fused salt heat buffer based double- walled boiler heating surface structure according to claim 1, characterized in that, ​

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